DIY Exhaust Mod – Gain of 10+ HP!!!

[msediqi]

Hey i got a simple question. im about to do this mod i have the screwable tip on my 03 boxster. Now when i drill the holes how far in deep to i drill? Do i drill al the way in ? am i supposed to make a hole in the frist chamber. How far exactly did u push the drill bit in ? Thanks for the help

[fishfood]

I can't see spending a grand for a new muffler,especially for the small gains it makes, but always wished the car sounded a bit more aggressive at lower rpms. Drilled two 1/2" holes, one on each side, using a 12" long bit, it made a small difference from idle-2500 rpm. Went up to a 9/16" and it sounds great now! That extra 1/16" adds over 25% more to the drilled cross sectional are, and it makes a big difference. Car sounds great at idle and normal cruising speeds, no resonace at all. Above ~3000 can't tell a difference at all, which is fine with me, it has always sounded good at higher revs. Just use a good sharp bit, push slowly and spin the drill slowly until the bit bites. The 9/16" bit fits tight on both sides as you put it in, but this helps guilde the bit and I didn't have a problem slipping. Thanks for the tip!

[MylesHye Clothing]

I did this tonight and it works great, just enough sound!!!!!

Everyone should do this mod!! i got my bit a lowes for 12.95.

Thanks for this great DIY.

[Jamesleeworks]

Crios

That is pretty cool, I think I am going to give that a try. did you have any modifications to your air intake?
You have any other clips?

[jhandy]

did the drills, love it, and plan on doing a second set of 1/2 inch holes strait back. Just a FYI. My drill bit was dancing all around. My tips do not come off, so the angle of attack was shallow. Some say to center punch. I used a large flat head screwdriver and pounded it into the pipe, poking a large hole, then drilled. Made the experience lasted about 2 mins per side. Obvious but someone may benifit from the suggestion.

James

[HDManny]

I drilled two holes (one per side) also but accidentally made them a little bigger then I intended and it sounds greats. As they mentioned on here previously, more noticeable when you go past 3000 rpms and it sounds louder not different.

[MN 986]

I started with 1/2"dia holes (one each side) on my 2002 2.7 and liked the extra sound. Eventually I wanted more, but could not find a larger diameter drill bit that was long enough to reach with the fixed exhaust tip. Then one day I ran across a 'stepped' drill bit and a drill bit extension, and slowly worked my way up to a 3/4"dia each side. I think it sounds even better. Definitely not too loud.

What have others tried?

[HDManny]

I used a 1/2" drill bit but as I said earlier, I got carried away then combined with the angle, I made my holes about the same size as yours. They are 1/2" by 1" so it should be the same, I like the sound and thought about going bigger.

[Alretired]

Does it matter if you drill almost straight back and not so much on the side? I assume you are still going into the same chamber of the muffler. I have the single tip (non-removable) and it is very hard to go at very much of an angle. Thanks.

[NWI Bill]

If you drill straight back, you'll drill through the back of the muffler and you don't want to do that. Drill to side like Crios instructed. I have a 98 Boxster with a single non-removable tip and didn't have any problem. Just use a long bit, 12" or so or use a drill bit extender. You can buy both at Sears. I just increased the diameter of the holes in mine to 1". I used a step bit to increase the size. I was getting a bit of "PFFHT" sound as I rev it. The increased diameter took care of that, the sound got a little deeper and no cabin drone.

Since we got into the low 30s here in Chicagoland today, I took the Box out for a drive to see how things sounded and rid myself of some cabin fever. :dance:

[mdimant]

Originally Posted by crios

30 min if that!! I'm wanting to drill wider to make it louder, but scared there might be drone past 1/2 inch. I'll post some more clips tomorrow on how loud it is, but I'd say it probably increased it by 10-20% at the most. Not as loud as PSE for sure, but better than stock.

I was contemplating the easiest hack on my stock 00' S muffler & reading this found me with drill in hand in no time. Your'e idea is brilliant. I drilled 2 holes 7/16 in each side & with a reemer punched them out to about 11/16. Used a 2x2 chunk of fir with a 'v'groove sawn in it to guide bit. It is a perfect note w/ minimal cabin drone which goes away @ 2800. I rarely run less than that anyway. It just screams when whooped! I also recently swapped stock header/cats for chinese headers ($69.00 +32.00 ship). They are awesome for the $ & collectors/welding is just great. Extended all 02 sensors placing pre-02's near header outlet (fitting provided in hdrs) & post 02's in top of pipe right behind 2nd cats, behind rear wheel well. I am now remodelling intake. All this fancy stuff available for $3-400 is great for a neurosurgeon, but I can't see it. I got some 3.5" silicon tubing (50%+- larger than stock dia) & 2 3" abs Street 45 deg. plumbing fittings, cut them down, rasped & sanded the insides to elim drag. The stock air box provided the short section w/ MAF hub when sawn up & removed, & I'm now patterning 3/32' uhmv plastic (or whatever it's called) for a new AB to house a 4.5x5.25, 6" long Conical filter from local ap store. I opted for an oilless K&N look alike for $20.00. It will be more of a plenum than an air tube, not much sucking hopefully, the fixed dia @ MAF must be maintained to get the cfm reading though. It will throw cel's I know, but with what I've saved I'll find someone to remap ecu. Working on this car is the most fun I've ever had with mech tools. What a great car. $15K for 31K miles, are u kidding? Rich mans garbage i guess. I won/t have 18 in it for a really fun fast ride thats so addictive to drive!

[tuneme]

Do you guys think you could do this with removed cat's?? its a 03 non-s with a remapp and intake and both cats removed... please let me know

[tamarsha]

I have an 03 S with a BNC filter, secondary cats removed, 200 cell primary cats, and FVD software and I love still love my exhaust mod. Go far it! It is a cheap (free) easy mod.

[tuneme]

Ok got a drill and did it, but i only drilled one hole as its already noisey without cats..
and all i can say is WOW sounds close to a GT3, incredible gonna take it for a drive and see how she go's otherwise i recommend this mod highly!!!

ps. il try take a video

[tuneme]

im even considering drilling a 2nd hole, but im scared about back pressure problems
iv booked the car for dyno, so ill see whats what hopefully there some gains

[dja1980]

Oooh... definitely let us know the results of the dyno!

[crios]

I get a BIG smile everytime I see someone do this mod!

[tuneme]

Ok drilled 2nd hole and reset the ECU to re-learn as my tuner said.. and WOW IT IS JUST INCREDIBLE!! dyno tomorrow morning as its a public holiday today

let you know how it go's

[carguy]

So who's gonna make the before and after videos?? Outside car and inside car..

[jgaude]

I'm bummed... I just did the mod on my '01 S, with 1/2" holes.. no sound difference at all! :-(

..Joe